Embodiments according to the invention are related to an audio decoder, an audio encoder, a method for decoding an audio signal, a method for encoding an audio signal and a corresponding computer program. Some embodiments are related to an audio signal.
Some embodiments according to the invention are related to an audio encoding/decoding concept, in which a side information is used for resetting a context of an entropy encoding/decoding.
Some embodiments are related to the control of the reset of an arithmetic coder.
Traditional audio coding concepts include an entropy coding scheme (for example for encoding spectral coefficients of a frequency domain signal representation) in order to reduce redundancy. Typically, entropy coding is applied to quantized spectral coefficients for frequency domain based coding schemes or quantized time domain samples for time domain based coding schemes. These entropy coding schemes typically make use of transmitting a code word in combination with an according code book index, which enables a decoder to look up a certain code book page for decoding an encoded information word corresponding to the transmitted code word on said code book page.
For details regarding such an audio coding concept, reference is made, for example, to international standard ISO/IEC 14496-3:2005(E), part 3: audio, part 4: general audio coding (GA)-AAC, Twin VQ, BSAC, in which the so called concept for “entropy/coding” is described.
However, it has been found that a significant overhead in bitrate is produced by the need for a regular transmission of a detailed code book selection information (e.g. sect_cb).